With the imminent launch of the JWST, the field of thermal-infrared (TIR) astronomy will enjoy a revolution. It is easy to imagine that all areas of infrared (IR) astronomy will be greatly advanced, but perhaps impossible to conceive of the new vistas that will be opened. To allow both follow-up JWST observations and a continuance of work started on the ground-based 8m’s, we continue to plan the science cases and instrument design for a TIR imager and spectrometer for early operation on the TMT. We present the current status of our science cases and the instrumentation plans, harnessing expertise across the TMT partnership. This instrument will be proposed by the MICHI team as a second-generation instrument in any upcoming calls for proposals.
Z-Spec is a cryogenic, broadband, millimeter-wave grating spectrometer. It is capable of obtaining many
spectral lines simultaneously because of its unprecedented broad bandwidth (185-305GHz). The bandpass covers the
1mm atmospheric transmission window with a resolving power of 250-400. Z-Spec uses 160 silicon nitride micromesh
bolometers cooled down to less than 100mK for background-limited performance. The unique capability of Z-Spec to
detect multiple lines simultaneously allows us to obtain information efficiently on the physical and chemical conditions
of nearby Ultra-luminous Infrared Galaxies (ULIRGs) powered by starbursts or Active Galactic Nuclei. Here we report
on new millimeter-wave broadband data for ULIRGs acquired with Z-Spec and the noise performance and achieved
sensitivity in observations with the CSO. We found that during the observations the noise scales with the atmospheric
opacity and can be explained well by our sensitivity model, considering the photon noise originating from the sky and
the telescope, as well as the detector and electronics noise. The photon noise is found to dominate the total noise.